This invention relates to the combination of flexible duct and a special carton cooperative with the duct to enable dispensing of controlled lengths of duct from the carton.
Flexible convoluted duct has the capacity to be extended or compressed to various lengths. Such duct typically is constructed of a helical support member as of metal or plastic, and an enclosure jacket which normally surrounds and/or embeds the helical support. When the duct is axially compressed, the helical support has inherent resilient bias tending to return the duct back to its original length. Such duct is typically shipped in compressed condition in a carton, as in a generally U-shaped configuration. Opening of the carton can result in the compressed duct springing forth not unlike a jack-in-the-box without attachment to the box.
One technique for controlling extension of the duct from the carton is that set forth in U.S. Pat. No. 4,771,884, i.e., providing a restricted opening in an end of the carton, smaller than the duct diameter, to require the duct to be physically pulled through this smaller opening while successive portions of the duct are transversely constricted. Applying these tensile and deformation stresses to the duct is not always desirable.
The inventor herein has conceived of a unique carton and duct arrangement to achieve controlled discharge of the duct from the carton without requiring the tensile stress and transverse deformation stress on the duct.